Performance and design of electric welders with controlled transients

IN AN ATTEMPT to verify the theory previously given of electric welders with controlled transients, tests have been made on a neutralized welder and a standard type welder with and without a reactor transformer. Oscillograms show that while the standard machine has a large rise of current when short-circuited for 2 or 3 cycles of a 60 cycle wave, the machines with controlled transients have a very much reduced rise of current, and to this their improved performance partly is ascribed. A second important factor is the recovery of voltage after short circuit. It is shown that the function of the reactor transformer is to neutralize the mutual induction between the series and shunt fields of the welder, thereby rendering the field current more nearly independent of occurrences in the welding circuit.